He had a bad plan? Because he's the bad guy? And he's not particularly far-sighted? I'm not sure what you're looking for here, he did a bad thing, and now hopefully the heroes will be able to do something about it in the next movie.
I dunno what, I'm not particularly looking forward to it. But good movies aren't predicated on villains having airtight schemes?
Thanos is obviously not all there, so even if he's smart and powerful enough to get all the Infinity Gems it doesn't mean he's thought a plan like this on such a grand level through. He's called "The Mad Titan" in the comics for a reason.
Also, you must realize his reasoning for killing off half of all life in the universe is WAY different than why he did it in the comics(He was in love with the personification of Death, an actual character in the Marvel Universe, and to test his devotion she charges Thanos to kill of half of all life in the universe). I will agree that it's strange to alter the character's driving motivations and not change their resulting actions to reflect it, though.
I’ve seen some interesting theories that despite Thanos’ stated motivations, Hela could return and take the role of Lady Death. From the trailer for Endgame I think it’s unlikely, though.
EDIT: Also,
Ultimately, Thanos is a zealot. He believes that his “method” is not only universally effective, but universally needed. But I don’t think he overlooks the collateral damage- I think he counts on it. With the snap, he leaves a mark on the universe that (he thinks) will last forever. But precisely because the effects of his actions linger, the (awful, absurd, shortsighted) justifications of those actions linger as well. I think he knows this, and he realizes that some (equally misguided) future ruler will inevitably be the “next Thanos.” By causing such immense destruction, he’s insured that his (twisted) ideals will last forever. And in a universe where rock collecting can make you a god, it’s not unreasonable that another individual in another time could “continure his work.”
Yes, his plan is ridiculous. His justifications are awful. And he’s insane. But he’s found a pretty good way to make sure that his awful, ridiculous, insane ideals are carried out.
I’m looking for an interesting villain, not something that is dull and cartoony. It’s even more surprising when you see people defending his plan or saying he sounds reasonable - it’s just so superficial that you can see through it with only a few seconds of thought. What Stan Lee did in superhero terms was to make the heroes characters with real personalities and motivations, which makes it ironic for me that the MCU as a whole coasts by on just creating SFX sequences, with a roster of fairly interchangable personas. Ever seen the Honest Movie Trailer that highlights the similarities between the group dynamics of the Avengers and Guardians of the Galaxy? It’s why I feel like the X-Men is the strongest narrative property in terms of the films (and I suspect the comics, though I don’t read anything from Marvel or DC at the moment). The dynamic between Professor X and Magneto (and their differing plans for saving their kind) has some scope for nuance. You may not agree with Magneto but his motivations are understandable and logical
Good stories are built around tension, and getting the audience invested. Sadly with movies, they have gotten really lazy and just get by on nostalgia for the latter. There are so few films launched in a year now with original stories or compelling villains, and it all feels like cheap sequel baiting. If it wasn’t for the Planet of the Apes reboots, I don’t know how far back I’d have to go to find a decently written franchise movie.
I guess everyone's tastes differ, for me Malthusian economics is a more interesting villain motivation than what you typically see in a comic book movie.
I terms of other franchises, I don't really think the last few years have been too bad. The Mission Impossible, Mad Max, Rocky, and Blade Runner franchises have all had great installments.